Function

• Preplant herbicides inhibit weed growth through the use of certain chemicals that selectively disrupt membrane oxidation in certain plants, a process known in the industry as PPO inhibition. However, crop plants take up these agents through their roots without being harmed. Preplant herbicides are also formulated to deter a chemical reaction in the soil called photodecomposition, which would otherwise cause the herbicides to degrade and dissipate from the soil.
  
  

Sulfentrazone

• Sold under the trade names Authority and Spartan, this herbicide is effective against many broadleaf species of weeds.
  
  

Flumetsulam

• Sold as Python WDG, this chemical is applied as a single ingredient as a broad-spectrum weed control. It may also be combined with other herbicides. However, efficiency is reduced in soil conditions with a pH of more than 7.8.
  
  

Canopy 75

• This preplant herbicide contains a mixture of metribuzin and chlorimuron, which controls a variety of invasive weeds, such as morning glory, ragweed, velvetleaf and jimsonweed.
  
  

Sonic 70

• This preplant herbicide combines sulfentrazone and chloransulam. It is used to control grassy and broadleaf weeds, most notably nutsedge.